Java 7 jps - JVM Process Status Tool

本文內容

• 語法
• 參數
• 描述
• 選項
• 主機標識符
• 輸出格式
• 示例
• 參考資料

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語法

jps [ options ] [ hostid ]

參數

options

命令行參數。

hostid

The host identifier of the host for which the process report should be generated. The hostid may include optional components that indicate the communications protocol, port number, and other implementation specific data.

描述

The jps tool lists the instrumented HotSpot Java Virtual Machines (JVMs) on the target system. The tool is limited to reporting information on JVMs for which it has the access permissions.

If jps is run without specifying a hostid, it will look for instrumented JVMs on the local host. If started with a hostid, it will look for JVMs on the indicated host, using the specified protocol and port. A jstatd process is assumed to be running on the target host.

The jps command will report the local VM identifier, or lvmid, for each instrumented JVM found on the target system. The lvmid is typically, but not necessarily, the operating system's process identifier for the JVM process. With no options, jps will list each Java application's lvmid followed by the short form of the application's class name or jar file name. The short form of the class name or JAR file name omits the class's package information or the JAR files path information.

The jps command uses the java launcher to find the class name and arguments passed to the main method. If the target JVM is started with a custom launcher, the class name (or JAR file name) and the arguments to the main method will not be available. In this case, the jps command will output the string Unknown for the class name or JAR file name and for the arguments to the main method.

The list of JVMs produced by the jps command may be limited by the permissions granted to the principal running the command. The command will only list the JVMs for which the principle has access rights as determined by operating system specific access control mechanisms.

NOTE: This utility is unsupported and may not be available in future versions of the JDK. It is not currently available on Windows 98 and Windows ME platforms.

選項

The jps command supports a number of options that modify the output of the command. These options are subject to change or removal in the future.

-q

Suppress the output of the class name, JAR file name, and arguments passed to the main method, producing only a list of local VM identifiers.

-m

Output the arguments passed to the main method. The output may be null for embedded JVMs.

-l

Output the full package name for the application's main class or the full path name to the application's JAR file.

-v

輸出 JVM 參數。

-V

Output the arguments passed to the JVM through the flags file (the .hotspotrc file or the file specified by the -XX:Flags=< filename> argument).

-J option

Pass option to the java launcher called by jps. For example, -J-Xms48m sets the startup memory to 48 megabytes. It is a common convention for -J to pass options to the underlying VM executing applications written in Java.

主機標識符

主機標識符（host identifier），或 hostid 是一個指示目標系統的字符串。其語法大都是 URI 語法：

[protocol:][[//]hostname][:port][/servername]

protocol

The communications protocol. If the protocol is omitted and a hostname is not specified, the default protocol is a platform specific, optimized, local protocol. If the protocol is omitted and a hostname is specified, then the default protocol is rmi.

hostname

A hostname or IP address indicating the target host. If hostname is omitted, then the target host is the local host.

port

The default port for communicating with the remote server. If the hostname is omitted or the protocol specifies an optimized, local protocol, then port is ignored. Otherwise, treatment of the port parameter is implementation specific. For the default rmi protocol the port indicates the port number for the rmiregistry on the remote host. If port is omitted, and protocol indicates rmi, then the default rmiregistry port (1099) is used.

servername

The treatment of this parameter depends on the implementation. For the optimized, local protocol, this field is ignored. For the rmi protocol, this parameter is a string representing the name of the RMI remote object on the remote host. See the -n option for the jstatd command.

輸出格式

jps 命令的輸出內容以下所示：

lvmid [ [ classname | JARfilename | "Unknown"] [ arg* ] [ jvmarg* ] ]

Where all output tokens are separated by white space. An arg that includes embedded white space will introduce ambiguity when attempting to map arguments to their actual positional parameters.
NOTE: You are advised not to write scripts to parse jps output since the format may change in future releases. If you choose to write scripts that parse jps output, expect to modify them for future releases of this tool.

示例

Listing the instrumented JVMs on the local host:

jps
18027 Java2Demo.JAR
18032 jps
18005 jstat

Listing the instrumented JVMs on a remote host:

This example assumes that the jstat server and either the its internal RMI registry or a separate external rmiregistry process are running on the remote host on the default port (port 1099). It also assumes that the local host has appropriate permissions to access the remote host. This example also includes the -l option to output the long form of the class names or JAR file names.

jps -l remote.domain
3002 /opt/jdk1.7.0/demo/jfc/Java2D/Java2Demo.JAR
2857 sun.tools.jstatd.jstatd

Listing the instrumented JVMs on a remote host with a non-default port for the RMI registry

This example assumes that the jstatd server, with an internal RMI registry bound to port 2002, is running on the remote host. This example also uses the -m option to include the arguments passed to the main method of each of the listed Java applications.

jps -m remote.domain:2002
3002 /opt/jdk1.7.0/demo/jfc/Java2D/Java2Demo.JAR
3102 sun.tools.jstatd.jstatd -p 2002

參考資料

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• Java 7 監控工具
• Java 7 jps
• Java 8 Docs
• Java 8 Docs troubleshoot
• Java 8 監控工具
• Java 8 jps